RE: Invalid UTF-8 string passed to pango_layout_set_text()

["Liu, Raymond" <raymond liu intel com>]

>Hi list,
>I'm learning GTK+ using "Foundations of GTK+ Development" by Andrew Krause and >today I did the exercise2-1(chapter2) which should meet the demand as follows:
>when press the key,the label's text and window's title can interchange.
>However,I got the warning:"Invalid UTF-8 string passed to pango_layout_set_text()".
>The label's text will be messy character when I first press SHIFT and both become >messy when I press key at the second time.
>The code is as follows and please note my comments:
>#include<gtk/gtk.h>
>#include<gdk/gdkkeysyms.h>
>static gboolean changeTitle(GtkWidget* window,
>            GdkEventKey* keyEvent,
>    GtkLabel *label)
>{
>const gchar *textLabel=gtk_label_get_text(GTK_LABEL(label));
>const gchar         *textWindow=gtk_window_get_title(GTK_WINDOW(window));
>

As you can see here, these gchar* are owned by the label/window, and upon you setting the window title, the textWindow point to something might already been freed, so cause these strange problem.

You need something like 

gchar         *textWindow= g_strdup(gtk_window_get_title(GTK_WINDOW(window)));

to store the tmp string data, and free it after you done with gtk_label_set_text in your code below

>if(keyEvent->keyval==GDK_Shift_L)
>{
>                //surprise,if I skip(via "//") one of the two lines, another 
>                //will work fine.....
>       gtk_window_set_title(GTK_WINDOW(window),textLabel);
>      gtk_label_set_text(GTK_LABEL(label),textWindow);
>}
>return FALSE;
>}

>Thanks for any clue!

>Best regards,
>Randy 

Raymond